Wikipedia seems to cover this quite well:
https://en.wikipedia.org/wiki/David_Mamet#.22Mamet_speak.22
The specific quote directly from Mamet:
When asked how he developed his style for writing dialogue, Mamet said, "In my family, in the days prior to television, we liked to while away the evenings by making ourselves miserable, based solely on our ...

Melfi has a history of alcohol abuse.
Kupferberg is aware of this and is afraid that Melfi might use alcohol to escape her guilt about abandoning Toni. He uses the term sugar substitutes as a euphemism for alcohol.
Alcohol is not a sugar in the chemical sense, but rather a product of fermenting sugar. It can however, toxic effects left aside, serve as a ...

I don't think he's hinting at anything but rather advising Melfi about her health. Sugar substitutes (AKA sweeteners) might be as detrimental to your health as sugar and might lead to weight gain.* From the Wikipedia page about sugar substitutes:
A 2012 study at Universidade Federal do Rio Grande do Sul showed that addition of either saccharin or ...

It was the bedding ceremony itself.
The bedding is a Westerosi wedding tradition, practiced throughout the
entire continent. It's intended to provide evidence that the bride and
bridegroom have consummated their marriage.
The bedding is commonly held after the wedding feast is over. Male
guests carry the bride while female guests carry the ...

After having told Valentine "You are completely crazy," she turns to the prime minister and says
Och när det gäller statsministern, (är jag) chockad över att du över huvud taget överväger det här. Du är vald av folket! Det är ditt jobb…
and then tries to get up from her chair before finishing her last sentence.
Translation:
As for the prime ...

From the original script, it's not immediately clear. On the one hand, Johnston ("R.J.") is clearly fluent in Mandarin:
RJ stares at the faces which begin to peer in through the car windows.
A grinning TWELVE YEAR-OLD slaps a poster against the glass.
R.J.(points at the ideogram on the poster) "China awake..."
and at the same time, the Emperor ...

Nux says very softly, "witness me," which is what a War Boy shouts when about to die heroically in battle. (The comrades shout "Witness!" while making the sign of V8, to send each other shiny and chrome to Valhalla.)
Nux was asking Capable to witness his deed. She has become, in effect, his Valkyrie, who will bear him to the afterlife, valiantly slain for a ...